APPARATUS AND METHOD OF PREPARING A SOLUTION CONTAINING CATIONS AND ANIONS

Abstract

Ions are important for human life. The current method to choose the ions type and the concentration is the traditional chemical dissolving ways. The invention proposes an apparatus and a method of preparing a solution (5) containing cations and anions. The apparatus comprises: at least one cation releasing module (10), each of which is configured to release at least one type of cations; at least one anion releasing module (12), each of which is configured to release at least one type of anions; and a controller (14) configured to control at least one said cation releasing module (10) and at least one said anion releasing module (12) to release corresponding types of ions. The embodiment of the invention automatically prepares a solution by respectively controlling the cations and the anions.

Description

TECHNICAL FIELD

The disclosure relates to preparations of a solution containing cations and anions, particularly to preparations of a solution containing selective cations and anions.

BACKGROUND OF THE INVENTION

Ions are electrically charged particles which take various functions in vivo, as well as in industrial and household applications.

Currently, solutions containing ions are prepared in a traditional chemical dissolving way. For example, a solution containing K⁺ and Cl⁻ can be prepared by dissolving potassium chloride (KCl) in a solvent such as water or diluting concentrated KCl solution.

However, in this way, anions and cations are added according to a molar ratio which is not controllable. For example, by dissolving KCl into water, K⁺ and Cl⁻ are added with a molar ratio of 1:1. By dissolving Na₂SO₄, Na⁺ and SO₄²⁻ are added with a molar ratio of 2:1.

Therefore, it turns out important and meaningful to have a new method and apparatus which enables a better control of ion release into a solution.

SUMMARY OF THE INVENTION

According to the aforementioned traditional method, to prepare a solution containing certain type of cations (e.g., K⁺) and anions (e.g., Cl⁻), the corresponding electrolyte (e.g., KCl) that can dissociate into the cations and anions is used. Alternatively, one electrolyte with the required cations and another electrolyte with the required anions are used together to provide the solution of the required cations and anions, which involves other ions not required. In view that different combinations of cations and anions may be required in different cases, users have to manage enormous kinds of electrolytes.

Besides, for an electrolyte such as KCl, as long as a concentration of cations such as K+ is determined, a concentration of anions such as Cl− is hence determined. In case it's needed to prepare a solution with K+ in concentration x and Cl− in concentration y where x is different from y, additional type of chemicals would need to be added into the solution, such as K₂SO₄, HCl, etc., which means the concentrations of cations and anions has to be controlled by precise weight measuring of each additive beforehand.

Additionally, in preparing the solution, for obtaining some ions such as H⁺, the user may have to use caustic chemicals, e.g. HCl, H₂SO₄ as raw materials or intermediate materials of the preparation, which is dangerous for the user.

To better address one or more of aforementioned problems, it would be advantageous to have an apparatus that automatically prepares a solution with cations and anions. It would be also advantageous to separately control the types of the cations and the anions.

Further, it would be advantageous if the apparatus separately and automatically controls respective concentration of the anions and cations.

Further, it would be advantageous if a user of the apparatus is free of disagreeable caustic chemicals.

In an embodiment of the invention, an apparatus for preparing a solution containing cations and anions comprises:

• • at least one cation releasing module, each of which is configured to release at least one type of cations;
  • at least one anion releasing module, each of which is configured to release at least one type of anions;
  • a controller configured to control at least one said cation releasing module and at least one said anion releasing module to release corresponding types of ions.

The cation releasing module and the anion releasing module can respectively release certain types of cations and anions into the solution. Thus, the types of cations and anions in the solution can be controlled separately.

Further, it would be advantageous to select by the apparatus, from multiple types of cations and/or anions, required types of cations and anions for the solution. To better address this, in a preferred embodiment, the apparatus comprises at least two cation releasing modules respectively for different types of cations, and/or at least two anion releasing modules respectively for different types of anions. In this preferred embodiment, with just a few cation releasing modules and anion releasing modules, it can provide solutions with various combinations of cations and anions, taking account of both flexibility and simplicity.

In a preferred embodiment, the cation releasing module comprises: a metal and/or alloy electrode connected to the controller and configured to immerse in the solution; the controller is configured to apply a positive voltage on the metal and/or alloy electrode such that cations are released into the solution.

This embodiment provides a specific implementation for the cation releasing module. The metal and/or alloy electrode is small in size, thus multiple types of electrode can be assembled in the apparatus to provide the diversity for cation selection. Besides, the metal and/or alloy electrode has a high capacity of cation storage and is convenient for transportation and use, which would be beneficial for domestic applications. In one embodiment, an active metal anode can be used to generate metal cations. In an alternative embodiment, an inert metal anode is used, and water electrolysis would be done and H⁺ cations can be generated. This can avoid an involvement of a caustic acid, e.g. HCl, H₂SO₄, and thus is safe for the user.

In a preferred embodiment, the cation releasing module comprises a first container for containing a first electrolyte containing a first type of cations, the first container having a cationic membrane for separating the first electrolyte from the solution, and the controller is configured to apply a positive voltage in the first electrolyte such that the first type of cations are released into the solution through the cationic membrane.

This embodiment provides another specific implementation for the cation releasing module. Active metal cations such as Na⁺, K⁺, Ca²⁺ and Mg²⁺ that is hard to be controllably generated by a metal electrode can be stored and controllably released in this embodiment.

In a preferred embodiment, the anion releasing module comprises a second container for containing a second electrolyte containing a second type of anions, the second container has a anionic membrane for separating the second electrolyte from the solution, and the controller is configured to apply a negative voltage in the second electrolyte such that the second type of anions are released into the solution through the anionic membrane.

Unlike cations, it could be hard to release anions from electrodes, thus the embodiment provides a specific implementation for the anion releasing module.

In a preferred embodiment, the cation releasing module comprises cation complexed polymers and/or gels which store the first type of cations and are configured to immerse in the solution, the controller is configured to electrolyze water in the solution and to generating generate H⁺ ions which enter the cation complexed polymers and/or gels and exchange the first type of cations out of the polymers and/or gels and into the solution.

Additionally or alternatively, the anion releasing module comprises anion complexed polymers and/or gels storing the second type of anions and is configured to immerse in the solution, the controller is configured to electrolyze water in the solution and generate OH⁻ ions which enter the anion complexed polymers and/or gels and exchange the second type of anions out of the polymers and/or gels and into the solution.

The embodiment provides still other specific implementations for the cation releasing module and the anion releasing module. The polymers and/or gels are easy to be replaced and cost effective.

In a preferred embodiment, the controller provides the cation releasing module and the anion releasing module with currents to release ions; the controller is configured to determine an amplitude of the current flowing through each cation releasing module and flowing time, according to a first concentration of the corresponding cations; and/or

the controller is configured to determine an amplitude of the current flowing through each anion releasing module and flowing time according to a second concentration of the corresponding anions;

wherein the controller is configured to control the amplitude of the currents and flowing time for the cation releasing module and the anion releasing module to maintain the total electricity of the generated cations and the total electricity of the generated anions equal.

This embodiment provides a specific implementation for respectively controlling the concentration of each of the cations and anions automatically without involving precise weight measuring. This embodiment is quite automatic and flexible for the user to prepare the solution with required concentrations of ions.

In an embodiment, the apparatus comprises a third container for containing the solution. In a varied embodiment, the apparatus can be placed into the solution, and the size of the apparatus can be small.

Solutions for various usages, e.g. mineral water for drinking, water for tofu making, skin care, disinfection and laundry, should contain different types of suitable cations and/or anions. Thus it would be advantageous to provide the solution according to the practical need. To better address this, in a preferred embodiment, the apparatus further comprises: a first unit configured to determine a usage of the solution; a second unit configured to determine a first type of cations and/or a second type of anions according to the determined usage; and said controller selects the cation releasing module and/or the anion releasing module according to the first type of the cations and/or the second type of the anions.

In an embodiment of the invention, it is provided a method of preparing solution containing cations and anions, comprising the steps of:

• • selecting at least one from at least one cation releasing module to release respective cations into the solution;
  • selecting at least one from at least one anions releasing module to release respective anions into the solution.

BRIEF DESCRIPTION OF THE DRAWINGS

Features, aspects and advantages of the present invention will become obvious by reading the following description of non-limiting embodiments with the aid of appended drawings.

FIGS. 1-4 illustrate the block diagrams of different apparatuses according to different embodiment of the invention;

FIG. 5 illustrates one specific embodiment of a cation releasing module 10 of the apparatus 1 as shown in FIGS. 1-4;

FIG. 6 illustrates another specific embodiment of the cation releasing module 10′ of the apparatus 1 as shown in FIGS. 1-4;

FIG. 7 illustrates one specific embodiment of the anion releasing module 12 of the apparatus 1 as shown in FIGS. 1-4;

FIG. 8 illustrates an embodiment of the apparatus 1 comprising cation releasing modules 10 and 10′ and anions releasing modules 12 and 12′ with the currents flowing direction.

FIG. 9 is a flow chart illustrating a method 9 according to the embodiment of the invention.

Wherein, the same or similar reference sign refers to the same or similar component/module.

DETAILED DESCRIPTION OF EMBODIMENTS

The following lists some typical ions and the respective usages:

• • 1) Ca²⁺: Calcium is a component of bones and teeth. It also functions as a biological messenger. The concentration of Ca²⁺ in water affects the efficiency of detergents and sometimes causes insoluble precipitation.
  • 2) K⁺ and Na⁺: Potassium and sodium ions' main function in animals is to maintain osmotic balance, particularly in the kidneys.
  • 3) Mg²⁺: Most importantly, magnesium ions are a component of chlorophyll. It also relates to water hardness.
  • 4) Cl⁻: chloride ions are important in a balance of an inner environment of human body, and chloride is also a composition of the gastric acid.
  • 5) CO₃²⁻: In blood approximately 85% of carbon dioxide is converted into carbonic acid radical ions, allowing a greater rate of transportation.
  • 6) PO₄³⁻: Adenosine triphosphate is a common molecule which stores energy in an accessible form. Bone is calcium phosphate.
  • 7) Fe^2/3+: Haemoglobin, the main oxygen carrying molecule has a central iron ion.

The tervalent Ferric ion can coagulate the proteins and be used in hemostatic agents.

According to an aspect of the invention, it is provided an apparatus 1 of preparing a solution containing cations and anions, comprising:

• • at least one cation releasing module 10, each of which is configured to release at least one type of cations into the solution;
  • at least one anion releasing module 12, each of which is configured to release at least one type of anions;
  • a controller 14 configured to control at least one said cation releasing module and at least one said anion releasing module to release corresponding types of ions.

In different embodiments, the number of either cation releasing modules 10 or anion releasing modules 12 can be quite varied depending on the needs. FIGS. 1-4 show the block diagrams of the different apparatuses 1 according to different embodiments of the invention. In an embodiment shown in FIG. 1, one cation releasing module 10 and one anion releasing module 12 is comprised in the apparatus 1. In this embodiment, the types of cations and anions in the solution are fixed. In a more complicated embodiment as shown in FIG. 2, the apparatus 1 comprises one anion releasing module 12 and several cation releasing modules 10, 10′ and 10″ to release a fixed anions together with any or any combination of the cations. Also, similarly, in a more complicated embodiment as shown in FIG. 3, the apparatus 1 comprises one cation releasing module 10 and several anion releasing modules 12, 12′ and 12″ to release a fixed cations together with any or any combinations of the anions. Further, in an embodiment as shown in FIG. 4, the apparatus 1 comprises several cation releasing modules 10, 10′ and several anion releasing modules 12, 12′ to release different combinations of anions and cations. It should be appreciated that in other embodiments the number of either or both of anion releasing module and cation releasing module can be different from that illustrated in FIGS. 1-4.

According to an aspect of the invention, as shown in FIG. 9, it is provided a method of preparing solution containing cations and anions, comprising the steps of:

• • S94: selecting at least one from at least one cation releasing module to release respective cations into the solution;
  • S96: selecting at least one from at least one anions releasing module to release respective anions into the solution.

Having described the varying structures of the apparatus and the method according to embodiments of the invention, the following part will elucidate different specific embodiments for the cation releasing module and the anion releasing module and the control applied thereto.

The Cation Releasing Module

In one embodiment, the cation releasing module 10 comprises a metal and/or alloy electrode 2 connected to the controller and configured to immerse in the solution. And the controller is configured to apply a positive voltage on the metal and/or alloy electrode such that cations are released into the solution.

As shown in FIG. 5, the electrode 2 is made from active metal A and used as the anode. The electrode 2 immerses in the solution 5, and when a positive voltage is applied on the electrode 2 (with a negative voltage is applied in the solution 5), the metal atom in the electrode 2 loses electrons, and the cations A^m+ are released from the electrode 2 and into the solution 5. Preferably in some embodiments, active metal cations like Al³⁺, Zn²⁺, Fe³⁺, Sn²⁺, Cu²⁺ and Ag⁺ can be released in this strategy. The electrode equations are listed as follows:

Al-3e⁻→Al³⁺;

Zn-2e⁻→Zn²⁺;

Fe-3e⁻→Fe³⁺;

Sn-2e⁻→Sn²⁺;

Cu-2e⁻→Cu²⁺; and

Ag-e⁻→Ag⁺

Wherein, e⁻ stands for an electron.

In an alternative embodiment, an inert metal electrode such as Pt electrode is used as the anode, and water electrolysis would be done at the anode and ft cations can be generated in the solution. This can generate ft cations without dissolving a caustic acid addictive, e.g. HCl, H₂SO₄, and hence it is safe for the user.

The metal and/or alloy electrode is small in size, thus multiple types of electrode can be installed in the apparatus 1 to provide diversity for the cation selection.

As to the method aspect, the first selecting step comprises: applying a positive voltage on the metal and/or alloy electrode 2 such that the cations are released into the solution.

In another embodiment, as shown in FIG. 6, the cation releasing module 10′ comprises a first container 3 for containing a first electrolyte 6 containing a first type of cations A^m+, and the first container 3 is for example configured to immerse into the solution 5. The first container 3 has a cationic membrane 30 for separating the first electrolyte 6 from the solution 5, and the cationic membrane 30 only allows cations pass through, namely from the first container 3 to the solution 5. And the cation releasing module 10′ comprises an anode 32 with one end immersing in the first electrolyte 6 and the other end connected to the controller 14 (not shown in FIG. 6) which is configured to apply a positive voltage to the first electrolyte 6 via the anode 32. Cations H⁺ are generated in the first electrolyte 6. To maintain the electric neutrality in the first electrolyte 6, the cations A^m+ flow out of the first electrolyte 6 through the cationic membrane 30 into the solution 5.

This embodiment provides another specific implementation for the cation releasing module. Active metal cations such as Na⁺, K⁺, Ca²⁺ and Mg²⁺ that is hard to be controllably generated by a metal anode can be stored and controllably released in this embodiment.

As to the method aspect, the first selecting step S94 comprises applying a positive voltage to the first electrolyte such that the cations are released into the solution through the cationic membrane 30.

In still another embodiment, other materials that can release cations under electrical control could also be used as the cation releasing module, such as polymer, gel. Specifically, the cation complexed polymer or gel storing this type of cations is configured to immerse in the solution, and the controller 14 is configured to electrolyze water in the solution to generate H⁺ cations. The H⁺ cations enter into the cation complexed polymer and/or gel and exchange this type of stored cations out of the polymer or gel under the effect of the electric field, and this type of cations enters into the solution under the effect of the electric field. In one implementation, one cation releasing module can contain one kind of polymer which stores and release one type of cations. In case that several types of cations are needed, several cation releasing modules respectively with corresponding polymer should be deployed. In a varied implementation, one cation releasing module can contain one polymer stores several types of cations, or contain several polymers respectively stores one type of cations. In this varied implementation, the several types of cations would be released simultaneously.

The above description gives implementations for the cation releasing module 10, and the following description will elucidate implementations for the anion releasing module 12.

The Anion Releasing Module

In one embodiment, as shown in FIG. 7, the anion releasing module 12 comprises a second container 4 for containing a second electrolyte 7 containing a second type of anions Bⁿ⁻, and the second container 4 is for example configured to immerse into the solution 5. The second container 4 has an anionic membrane 40 for separating the second electrolyte 7 with the solution 5, and the anionic membrane 40 only allows anions pass through, namely from the second container 4 to the solution 5. And the cation releasing module 10 comprises a cathode 42 with one end immersing in the second electrolyte 7 and the other end connected to the controller 14 which is configured to apply a negative voltage to the second electrolyte 7 via the cathode 42. Anions OH⁻ are generated in the second electrolyte 7. To maintain the electric neutrality in the second electrolyte 7, anions Bⁿ⁻ flow out of the second electrolyte 7 through the anionic membrane 40 into the solution 5.

In an example, acid radicals such as Cl⁻, SO₄²⁻ are required in the solution 5. In the prior arts, the user may have to manipulate HCl or H₂SO₄, and this is dangerous. When using the embodiment of the invention, the anion releasing module 12 can use a solution of KCl or Na₂SO₄ as the second electrolyte 7. The acid radicals are released without the manipulation of the user, and the user is free of the caustic chemicals.

As to the method aspect, the second selecting step comprises: applying a negative voltage to the second electrolyte such that the anions are released into the solution through the anionic membrane 40.

In still another embodiment, other materials that can release anions under electrical control could also be used as the anion releasing module, such as polymer, gel. Specifically, anion complexed polymer or gel storing this type of anions is configured to immerse in the solution, and the controller is configured to electrolyze water in the solution and generate OH⁻ anions. The OH⁻ anions enter into the anion polymer or gel and exchange this type of stored anions out of the polymers or gels under the effect of the electric field, and this type of anions enters into the solution under the effect of the electric field. In one implementation, one anion releasing module can contain one kind of polymer which stores and release one type of anions. In case that several types of anions are needed, several anion releasing modules respectively with corresponding polymer should be deployed. In a varied implementation, one anion releasing module can contain one polymer stores several types of anions, or contain several polymers respectively stores one type of anions. In this varied implementation, the several types of anions would be released simultaneously.

Generally, unlike metal anodes that release metal cations, most cathode itself can't release anions, therefore the above embodiments with an anion-contained solution and an anion-complexed polymer and/or gel make it possible to release anions.

The above description elucidates the structure of the apparatus 1 and specific implementations of the cation releasing modules 10 and anion releasing modules 12. The following description will elucidate how to control each of the modules to obtain required concentrations of each of the cations and anions.

An apparatus 1 with two cation releasing modules 10 and two anion releasing modules 12 is taken as an example and illustrated in FIG. 8. The controller 14 provides the cation releasing modules 10 and the anion releasing modules 12 with currents to release ions, and the controller 14 controls the amplitude of current and current flowing time for each module to obtain required concentration. To make it easy to understand, all of the cation releasing modules 10 and 10′ are similar as that in FIG. 6 and the anion releasing modules 12 and 12′ are similar as that in FIG. 7. The apparatus further comprises a third container 50 for containing the solution 5, and those modules are placed within the container 50 and configured to immerse into the solution 5.

The concentrations of released cations and anions are closely related with the electricity (Q=t×I) provided for each module by the current over the time. The equations could be written as:

m×C _A1 ^m+ ×V=t×I _A1 ; n×C _A2 ⁿ⁺ ×V=t×I _A2;

o×C _B1 ^o− ×V=t×I _B1 ; p×C _B2 ^p− ×V=t×I _A2.

wherein m, n, o and p are the charge numbers of the cations and anions; C_A1^m+, C_A2ⁿ⁺, C_B1^o− and C_B2^p− are the concentrations of the cations and anions; V is the volume of the solution S, I_A1, I_A2, I_B1 and I_A2 are the currents flow through the modules; t is the time for which the current flows and releases the ions. Given a required concentration of the cations and anions, the controller 14 determines the amplitude of the current flowing through the corresponding module and flowing time, according to the concentration of the corresponding ions together with charge numbers of the ions and a volume of the solution S. For example, for A1^m+, given the required concentration C_A1^m+, the current I_A1 and time t shall meet the following expression:

t×I _A1 =m×C _A1 ^m+ ×V.

To maintain the electric neutrality, cations and anions released should satisfy the following equation:

m×C _A1 ^m+ +n×C _A2 ⁿ⁺ =o×C _B1 ^o− +p×C _B2 ^p−

Moreover, the total amount of ions released could be monitored and controlled by the total electricity flow through the ion modules, which can be recorded as:

Q _total =Σt×I _Ai =Σt×I _Bi =Σm _i ×C _Ai ^mi+ ×V=Σo _j ×C _Bj ^oj− ×V.

For example,

1. When I_A1=I_B1≠0 and I_A2=I_B2=0, then A1^m+ and B1^o− are released with a concentration ratio of o:m.

2. When I_A1=I_B2≠0 and I_A2=I_B1=0, then A1^m+ and B2^q− are released with a concentration ratio of q:m.

3. When I_A1=2I_B1=2I_B2 and I_A2=0, then A1^m+, B1^o− and B2^q− are released with a concentration ratio of 2oq:mq:mo.

4. By controlling the current distribution, complex combination of different cations and anions can be released.

This embodiment provides a specific implementation for respectively controlling the concentration of each of the cations and ions. This embodiment is quite automatic and flexible for the user to prepare the solution with required concentrations of ions.

As to the method aspect, the method further comprises:

determining the amplitude of the current flowing through each cation releasing module 10 and flowing time, according to a first concentration of the corresponding cations; and/or

determining the amplitude of the current flowing through each anion releasing module 12 and flowing time according to a second concentration of the corresponding anions;

and comprises:

controlling the amplitude of the currents and flowing time for the cation releasing module 10 and the anion releasing module 12, to maintain the total electricity of the generated cations and the total electricity of the generated anions equal.

In the implementation, the solution for various usages, e.g. mineral water for drinking, tofu making, skin care, disinfection or laundry, should contain different types of suitable cations and/or anions. Thus it would be advantageous for one single apparatus to provide diverse solutions according to different practical needs. To better address this, in a preferred embodiment, the apparatus further comprises:

a first unit configured to obtain information concerning a usage of the solution;

a second unit configured to determine a first type of the cations and/or a second type of the anions in the solution according to the obtained information;

and the controller 14 selects at least one said cation releasing module 10 and/or at least one said anion releasing module 12 according to the determined first type of the cation and/or the determined second type of the anions.

For example, to prepare mineral water for drink, the cations are Na⁺, K⁺, Ca²⁺ and Mg²⁺, meanwhile the anions are SO₄²⁻ and Cl⁻. To prepare water for skin care and oral care, the cations can be Ca²⁺, Mg²⁺, Zn²⁺ and the anions are NO₃⁻ or SO₄²⁻. To prepare water for disinfection and hygiene, the cations can be Ag+, H+, and the anions can be S₂O₈²⁻. In a further implementation, the solution is not used directly but undergoes a further processing, for example the usage of the solution is being electrolyzed to generate corresponding gases, such as Cl₂. In this case, the controller 14 selects modules to release corresponding ions into the solution, for example selects a Cl⁻ releasing module to release Cl⁻ into the solution so as to generate Cl₂.

The first unit configured to obtain the information can be a user interface configured to receive the input from the user. In case that the apparatus is attached to and output the solution to a device, such as water dispenser, tofu making machine, washing machine, adapted to utilize this solution, the interface can be a machine to machine interface to receive the instruction from the device. In another embodiment, the first unit can also be a memory prestoring the information concerning the usage of the solution.

As to the method aspect, as shown in FIG. 9, before steps S94 and S96, the method further comprises the steps of:

• • S90: obtaining information concerning a usage of the solution; and
  • S96: determining a first type of the cations and/or a second type of the anions in the solution according to the obtained information;

said two selecting step respectively selects the cation releasing module 10 and/or the anion releasing module 12 according to the determined first type of the cations and/or the determined second type of the anions.

Those ordinary skilled in the art could understand and realize modifications to the disclosed embodiments, through studying the description, drawings and appended claims. For example, each of the cation releasing modules can contain and release two or more types of the cations simultaneously, such as Na⁺, Ca²⁺ and Mg²⁺, and each of the anion releasing modules can contain and release two or more types of the anions simultaneously. All such modifications which do not depart from the spirit of the invention are intended to be included within the scope of the appended claims.

The word “comprising” does not exclude the presence of elements or steps not listed in a claim or in the description. The word “a” or “an” preceding an element does not exclude the presence of a plurality of such elements. In the practice of present invention, several technical features in the claim can be embodied by one component. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. “At least one of A, B and C” should cover any one of the following: A; B; C; A and B; A and C; B and C; A and B and C.

Claims

1. An apparatus of preparing a solution containing cations and anions, comprising: at least one cation releasing module, each of which is configured to release at least one type of cations;at least one anion releasing module, each of which is configured to release at least one type of anions;a controller configured to control at least one said cation releasing module and at least one said anion releasing module to release corresponding types of ions;wherein, the apparatus comprises at least two cation releasing modules (10, 10′) and/or the apparatus comprises at least two anion releasing modules (12, 12″).

2. (canceled)

3. An apparatus according to claim 1, wherein, the cation releasing module comprises: a metal and/or alloy electrode connected to the controller and configured to immerse in the solution;the controller is configured to apply a positive voltage on the metal and/or alloy electrode such that cations are released into the solution.

4. An apparatus according to claim 1, wherein the cation releasing module comprises a first container for containing a first electrolyte containing said type of cations, the first container having a cationic membrane separating the first electrolyte with the solution, the controller is configured to apply a positive voltage to the first electrolyte such that said type of cations are released into the solution through the cationic membrane.

5. An apparatus according to claim 1, wherein the anion releasing module comprises a second container for containing a second electrolyte containing said type of anions, the second container has an anionic membrane for separating the second electrolyte with the solution, the controller is configured to apply a negative voltage to the second electrolyte such that said type of anions are released into the solution through the anionic membrane.

6. An apparatus according to claim 1, wherein the cation releasing module comprises a cation complexed polymer and/or gel storing the cations and configured to immerse in the solution, the controller is configured to electrolyze water in the solution and generate H+ ions which enter the cation complexed polymer and/or gel and exchange said type of cations out of the polymer and/or gel and into the solution;and/orthe anion releasing module comprises an anion complexed polymer and/or gel storing the anions and configured to immerse in the solution,the controller is configured to electrolyze water in the solution and generate OH− ions which enter the anion complexed polymers and/or gels and exchange said type of anions out of the polymers and/or gels and into the solution.

7. An apparatus according to claim 1, wherein, the controller provides the cation releasing module and the anion releasing module with currents to release ions; the controller is configured to determine an amplitude of the current flowing through each cation releasing module and flowing time, according to a first concentration of the corresponding cations; and/orthe controller is configured to determine an amplitude of the current flowing through each anion releasing module and flowing time according to a second concentration of the corresponding anions;wherein the controller is configured to control an amplitude of the currents and flowing time for the cation releasing module and the anion releasing module to maintain the total electricity of the generated cations and the total electricity of the generated anions equal; andthe apparatus further comprises: a third container for containing the solution.

8. An apparatus according to claim 1, further comprising: a first unit configured to obtain information concerning a usage of the solution;a second unit configured to determine the a first type of the cations and/or the a second type of the anions in the solution according to the obtained information;said controller selects at least one said cation releasing module and/or at least one said anion releasing module according to the determined first type of the cations and/or the determined second type of the anions.

9. A method of preparing solution containing cations and anions, comprising the steps of: selecting at least one from at least one cation releasing module to release respective cations;selecting at least one from at least one anions releasing module to release respective anions; wherein the cation releasing module comprises at least two modules respectively for different types of cations, and/orthe anions releasing module comprises at least modules respectively for different types of cations.

10. (canceled)

11. A method according to claim 9, wherein the cation releasing module comprises: a metal and/or alloy electrode connected to an anode and configured to immerse in the solution;and the first selecting step comprises:applying a positive voltage on the metal and/or alloy electrode such that the metal cations are released into the solution.

12. A method according to claim 9, wherein the cation releasing module comprises a first container for containing a first electrolyte containing the type of cations, the first container having a layer of cationic membrane for separating the first electrolyte with the solution, and the first selecting step comprises:applying a positive voltage to the first electrolyte such that the cations are released into the solution through the cationic membrane.

13. A method according to claim 9, wherein the anion releasing module comprises a second container for containing a second electrolyte containing the anions, the second container has a layer of anionic membrane for separating the second electrolyte with the solution, and the second selecting step comprises:applying a negative voltage to the second electrolyte such that the anions are released into the solution through the anionic membrane.

14. A method according to claim 9, wherein, the first and second selecting step provides the cation anion releasing module and the anion releasing module with current to release ions; the method further comprises:determining the amplitude of the current flowing through each cation releasing module and flowing time, according to a first concentration of the corresponding cations; and/ordetermining the amplitude of the current flowing through each anion releasing module and flowing time according to a second concentration of the corresponding anions;and comprises:controlling the amplitude of the currents and flowing time for the cation releasing module and the anion releasing module, to maintain the total electricity of the generated cations and the total electricity of the generated anions equal.

15. A method according to claim 9, further comprising the steps of: obtaining information concerning a usage of the solution;determining a first type of the cations and/or a second type of the anions in the solution according to the obtained information;said two selecting step respectively selects the cation releasing module and/or the anion releasing module according to the determined first type of the cation and/or the determined type of the anions.